Method of producing electrical heating elements



June 9, 1931. EJL. WIEGAND METHOD OF PRODUCING ELECTRICAL HEATING ELEMENTS Filed Aug. 25, 1928 Patented June 9, 1931 PATENT OFFICE EDWIN L. WIEGAND, OF PITTSBURGH, PENNSYLVANIA METHOD OF PRODUCING ELECTRICAL HEATING ELEMENTS Application filed August 23, 1928. Serial No. 301,514.

This invention relates to a method of producing electrical heating elements of the type wherein the resistor is imbedded in a compact mass of granular refractory insulating material. The insulating material is desirably of high heat conducting quality and it may be contained in a receptacle or sheath of relatively thin sheet metal. Elements of this description are highly efficient, withstand a very considerable amount of physical abuse, and are practically indestructible from overheating and long continued service.

It will be apparent from the following disclosure'that electrical heating elements of various sizes and shapes may be produced by my present method, but for the purpose of illustration I have selected a cylindrical element like that employed in a percolator unit disclosed in my copending application Serial No. 289,819, filed July 2, 1928, which has issued as Patent 1,778,926.

The purpose of the instant invention is to provide a simple and convenient method by which electrical heating elements of the type aforesaid and of very high quality may be expeditiously and cheaply manufactured, and the method, in its more complete aspect, may be defined briefly as consisting in mounting or suitably combining a resistor on or with a self-sustaining friable or collapsible core or support'of granular refractory electrical insulating material, and then applying thereto or encasing the same in a quantity of similar mobile material and compacting or compressing the assembly (preferably in a sheet metal sheath) so that the support or core is crumbled or collapsed and merged with the mobile material so that the whole becomes a relatively dense or homogeneous mass with the resistor embedded therein.

One manner of performing the method is shown in the accompanying drawings wherein Fig. 1 is a side elevation of the friable or collapsible core or support with the resistor applied thereto; Fig. 2 is a central vertical section through a sheet metal receptacle that constitutes the sheath of .the completed element; Fig. 3 is a central vertical section through an apparatus used in produclng the element and showing the parts of the element contained therein before compression; Fig. 4 is a similar view showing the contents of thereceptacle compacted by means of a plunger that forms a part of the apparatus; Fig. 5 is a central vertical section through the completed element; and Fig. 6 is a sectional plan on the line 66 of Fig. 5.

.In the present example of the method, a receptacle 1, which is preferably of relatively thin sheet metal of suitable quality, and which constitutes the sheath of the heating element,'is placed within a cylindrical cavity of a retainer 2 to the upper end of which is applied an annulus 3 having a bore that is approximately of the same diameter as the internal diameter of the receptacle 1. In the receptacle 1 is placed a friable or collapsible core or support 5 (that carries the resistor as will hereinafter be explained) that is desirably formed of granular refractory electrical insulating material. In its present form it is shown as having an external spiral groove 6 that communicates, through a notch 7, with a longitudinal passageway 8, the opposite end of the spiral groove 6 opening into a recess 9 in the top of the support or core.

The resistor, designated 10, consists of a metal wire or filament that may or may not be wound into a helix of very small diameter, in a manner well known to those familiar with the subject, and it is applied to the core or support 5 before thelatter is deposited in the receptacle 1. In applying the resistor 10 to the core or support 5, it is wound about the exterior of the core or support within the groove 6 and one of its ends is offset inwardly into the notch 9 and thence turned axially of the core or support, while its opposite end is i turned downwardly through the notch 7 that is formed in the periphery of the enlarged lower end or base 11 of the core or support and then inwardly and upwardly through the passageway 8 in substantially parallel relation to the opposite end portion of the resistor.

A quantity of mobile granular refractory electricalinsulating material is next poured into the receptacle 1, filling the same and (dehavingducts 13 for the accommodation of the end portions of the-resistor 10, is inserted within said bore and is forced downwardly to compress the insulating material within the receptaclel and collapse or crumble the triable core or support 5 so that its identity becomes lost and it is merged with the insulating material that was previously mobile, the whole becoming a dense, homogeneous mass within which the resistor '10 is embedded.

The annulus 3 is then removed and the receptacle 1 is withdrawn from the retainer 2,

after which a metallic disk or closure 15, with a disk 16 of mica or other suitable insulating material, is placed within the open end of the receptacle in contact with the insulating material and the rim of the receptacle is then peened inwardlyto hold thedisks in place. It willbe noted that the metallic disk 15 has relatively large apertures and that the disk 16 of insulating material has relatively small apertures that register with those of the metallic disk, for the passage of the end portions or terminals of the 'resistor 10. a The mobile insulating material, as well as that whereo-fi the support or core 5 is made, may be the same as, or similar to, that described in my prior Patent No. 1614330, dated J anuary 11, 1927.

Having thus described by invention, what I claim is:

1. The method of producing an electrical, heating element which consists .in combining heating element which consists in applying a resistor to a friable core'of insulating'mate'rial, surrounding said core with a quantity 'of mobile insulating material, and compacting the assembly so as to collapse the core '.and integrate it and .themobile insulating material with the resistor embedded in the resultant mass. I

3, The method of producing an electrical heating element which consists in combining a resistor with a self-sustaining collapsible support of insulating material, placing said support and the resistor in a receptacle, introducing mobile insulating material into the receptacle, and compacting the contents of the receptacle so as to collapse the support and integrate it and the mobile insulatingmaterial with the resistor embedded in the resultant mass. i

4. The method of producing an electrical heating elenient which consists in. combining a resistor with a self-sustaining collapsible support of insulating material, placing said support and the resistor in a receptacle, introducin-g mobile insulating material into the receptacle, compacting the contents of the receptacle so as to colla se the support and integrate it and the mo ile insulatmg material with the resistor embedded in the resultant mass, and applying a closure to the receptacle, 5. The method of producing an electrical heating element which consists in placing within anopen sheath a self-sustaining collapsible support of insulating material carrying a resistor,'introducing into the sheath a quantity of mobile insulating material, and compacting the contents of the sheath so as to collapse the support and integrate it and the mobile insulating material with the resistor embedded in the resultant mass.

6. The method of producing an electrical heating element which consists in within an open sheath a self-sustaining collapsible support of insulati material ca'rrylng a resistor, introducing mto the sheath a quantity of mobile insulating material, compacting the contents of the sheath so as to placing collapse the support and integrate it and the a mobile insulating material with the resistor embedded in the resultant mass, and closing the sheath.

- 7 The method of roduci'ng an electrical heating element which consists in winding a resistor on a friable core with the ends of the resistor projecting beyond one end of the core, placing the core and resistor in a metal receptacle with the'opposite end of the core adjacent the bottom of the receptacle, introducing into the receptacle a quantity of mobile insulating material, and compacting the contents of the receptacle so as to crumble the core and integrate it and the mobile insulating-material with the resistor embedded in the resultant mass.

8. The method of producing an electrical heating element which consists in winding a resistor on a core with the ends of the resistor projecting beyond one end of thecore, plac ing the core and resistor in a metal receptacle with the opposite end of the core adjacent the bottom of the receptacle, introducing into the receptacle a quantity of mobile insulating material, compacting the same so as to efiect a body of msulatlng material with the resist or embedde'daherein, and applying a closure to the receptacle.

.9. The method of producingan electrical heating element which consists in appl 'ng a res1s tor to a core, placing the core and re- SlStOIlll a metal receptacle, introducin into the receptacle a quantlty of mobile insufizting material, compacting the same so as to effect a body of insulating material with the resistor embedded-therein, placing a closure within the open end of the receptacle, and peenin over the rim of the receptacle to hold sai closure in place.

10. The method of roducing an electrical heating element whic consists in windin Q resistor on a friable core with the ends of t e resistor projecting beyond one end of the core, placing the core and resistor in a'metal receptacle with the op osite end of the core adjacent the bottom 0 the receptacle, introducing into the receptacle a quantity of mobile insulating material, compacting the contents of the receptacle so as to crumble the core and integrate it and the mobile insulating material withthe resistor embedded in the resultant mass, placing a closure within the open end of the receptacle, and peenin over the rim of the receptacle to hold sai closure in place.

11. The method of producing electrical heating elements of the character described which consists in winding a resistor on a self-sustaining friable resistor support, placing the resistor support with resistor thereon in a suitable casing, surrounding the same with a quantity of mobile insulating material, applying sufiicient pressure axially of the support to collapse the support and integrate it with the insulating material seas to form a homogeneous mass with the resistor embedded therein and then closing the container.

12. The method of producing an electrical heating element which consists in supporting a resistor on a friable self-sustaining resistor, 7

support formed of insulation material, surrounding said resistor support and resistor with mobile insulation material and then apglying suflicient ressure to the assembly an axially thereo to collapse the su port and integrate it with the mobile in ation material so as to form a homogeneous mass with the resistor embeddedthereln.

In testimony whereof, I- hereunto aflix my a signature. 7

- EDWIN L. WIEGAND. 

